Optical activity

Question 1

Why does optical isomerism occur and hopw are they represented?

Answer 1

they have three-dimensional strcture

it can only be shown by 3d representations or by models

Question 2

What is the nature of light?

Answer 2

consists of vibrating electric and magnetic field

waves with vibrations occuring in all directions at right angles to the direction of the motion of the light wave

Question 3

What is a polaroid?

Answer 3

special light filter

all the vibrations are cut out except those in one plane, e.g. vertical plane

Question 4

How is this light used?

Answer 4

polarised light will be affected differently by different optical isomers of the same substance

Question 5

How is optical rotation measured?

Answer 5

using a polarimiter

Question 6

How does a polarimeter work?

Answer 6

1. polarised light is passed through two solutions of the same conc., each containing a different optical isomer of the same substance
2. the emerging light has been rotated, rotation is seen through a second polaroid
3. one solution will rotate the plane of polarisation through a particular angle, clockwise. This is the (+)-isomer
4. the other will rotate the plane of polarisation by the same angle, anticlockwise, this is the (-)-isomer